The Evolution link pipe set upgrades the Slip-On system to the Evolution system, which consists of a single-central muffler with valves and bigger Evolution link pipe tubes with a middle muffler, all designed to make the performance and workmanship of the complete system as perfect as it looks. With no second set of cats (unlike the stock system), the whole system is designed to give the smoothest flow and the power and torque gains of the BMW with the combination of the Slip-On Line system and Evolution link pipe set are absolutely guaranteed. Crafted entirely from titanium, the complete system has a unique sound to complement its substantial increase over a very wide rpm range. In-depth engineering has produced a sound distinctly different from the stock system, giving a deep and sporty sound with no unwanted overtones or drone, and also a significant change to the sound with the valves in the open or closed positions. The complete system needs no re-programming of the ECU because it doesn't trigger any warning lights. With tailpipes in titanium or carbon, and a handcrafted rear diffuser, all available as optional extras, the BMW with the Slip-On Line and Evolution link pipe set is as beautiful as it is powerful.